Why can't I install an older version of blender after uninstalling 2.8?
Just get the 2.79 portable version on www.blender.org

Since it's just a .zip file, you don't have to install it, and the first time you open it, it will automatically set itself up in the OS

However I doubt your graphics card are a problem (Blender doesn't require a graphic card to run). You could try updating your drivers, or at least try the 2.80 portable version before downloading Blender 2.79